Apparatus for frequency multiplication of alternating electric currents



bf. E59 i949. A. H B WALKER '2461?@61 APPARATUS FOR FREQUENCYMULTIPLICATION OF ALTERNATING ELECTRIC CURRENTS Filed May 2, 1945 y@ @fmN 7 PL @0l 9 Z0 Load 6715100@ i Patented Feb. 15,1949 l g 2,461,861

UNITED STATES rATi-:NT ori-lcs APPARATUS FOR FREQUENCY MULTIPLICA- TIONOF ALTERNATING ELECTRIC CUR- RENTS .1

Alec Hervey Bennett Walker, London, England, assignor, by mesneassignments, to The Union Switch and Signal Company, Swissvale, Pa., acorporation of Pennsylvania y Application May 2. 1945, Serial No.591,525

In Great Britain 'Julyl 11,l 1944 i claim. (cariz-,281i

1 2 This invention relates to apparatus for freterminals of a iirstphase of a two-phase alternatquency multiplication of alternatingelectric curing current supply source, and terminals 4 and 5 rents ofthe kind in which the frequency multiare the terminals of a second phaseof this twoplication is effected by causing continuously sucphase supplysource. This alternating current cessive half waves of current, of thefrequency to may be, for example, of a frequency of 50 cycles bemultiplied and ofv the same sign, to iiow in the per second.

circuit in which current of the multiple frequency Terminals 2 and 3 areconnected to the input is required, either by reversing alternatehalfterminals of a first full wave rectifier 6, and terwaves of a singlephase alternating current supply minals 4 and 5 are connected to theinput terby means of a full wave rectifier device or by minals ofasecondfull Wave rectifier 1. The posipreventing the flow of current inalternate halftive output terminals 8 and 9 of rectiflers 6 and 1, wavesin each phase of a polyphase current suprespectively, are connected tothe outside terply by means of a suitable rectifier. minals I0 and II,respectively, of a choke coil C.

The unidirectional current iiowing inthe cir- The negative outputterminals I2 and I3 of cuit to be supplied will thus comprise a multiplerectifers E and 1, respectively, are connected frequency component whichis however relatively together through wire I4 and through a resistorsmall and the invention has for its object to I5to central terminal I6of choke coil C.

provide improved apparatus ofl the character Choke coil C may beconstituted a primary above described in which the multiple frequencywinding of a transformer T having a secondary current is considerablyincreased and its wave winding I8 connected to terminals I9 and 20 ofform rendered nearly sinusoidal. a load circuit of any desired nature.

According to the present invention a period- A condenser 2l may beconnected across choke ically varying voltage consisting of continuouslycoil C, and a condenser 22 may be connected successive half waves of thefrequency to be across resistor I5 to improve the operation butmultiplied and of the same sign together with 25 such condensers 2l and22 may not be required. one or more simiar voltages of opposite sign andIn operation it is evident that the double fresuitably displaced inphase are arranged to be quency voltages at the output terminals of thetwo impressed on the circuit to be supplied with currectiers andimpressed upon choke coil C are rent of multiple frequency, the phasedisplaceopposed to each other in sign and owing to their ment of thesevoltages causing the resultant 90 displacement in phase combine to forma current in the circuit to consist of similar positive double frequencyvoltage at the terminals of choke and negative alternations of mutliplefrequency coil C and which voltage is of the same amplitude more nearlyof sinusoidal form than can be obas the original input voltage at therectiers but tained by a single unidirectional voltage wave. of somewhatmore peaked wave form.

The two or more voltages above referred to This characteristic isillustrated in Fig. 3, as must be equally displaced in phase from onewill be apparent by an inspection of the drawing another, this phasedisplacement being for cxwhen taken in connection with the foregoingdeample, 90 in the case of two voltages and 120 scription of theapparatus of Fig. 1. in the case of three voltages and these phase-Resistor I5 serves as a consuming load for the displaced voltages may bederived either from direct current component of the rectifier output.polyphase supply circuits if available or from a The wave form of thevoltage applied to the single phase supply circuit by providing suitableload circuit may be improved and rendered subphase splitting devices.stantially sinusoidal by including saturation choke I shall describe twoforms of aparatus embodycoils 23 and 24 in the input rectiiier circuitsas ing my invention and shall then point out the described in mycopending application for Letters novel features thereof in claim.Patent of the United States, Serial No. 591,524, In the accompanyingdrawings, Fig. 1 is a dialed May 2, 1945, now Patent 2,420,213, issuedgrammatic view showing one form of apparatus May 6, 1947, for Apparatusfor frequency multiembodying the invention when used with a twoplicationof alternating electric currents. It is phase supply source and Fig. 2is a diagrammatic 50 apparent that a double frequency alternating viewshowing a form of apparatus embodying the voltage is applied to the loadcircuit, such voltage invention when used with a three-phase supplybeing substantially sinusoidal.

source. Fig. 3 is a diagram illustrating a char- Referring to F'ig. 2,terminals A, B and C are acteristic of the apparatus of Fig. 1. theterminals of a three-phase source of supply Referring to Fig. 1,terminals 2 and 3 are the 55 not shown. This alternating current may beof l delivered from coil C to the load circuit.

any convenient frequency. windings 2B, 21 and 28 are the primarywindings of a three-phase transformer which is provided with ahexa-phase secondary winding comprising windings SI to S6, inclusive.Terminals of alternate windings SI, S3 and S5 are connected throughrectifiers 29, 30 and 3i to terminal I0 of choke coil C. Similarly;terminals of windings S2, S4 and S6 are connected through rectifiers 32,33 and 34 to terminal ,H of coil C. A neutral terminal of each of thesecondary windings is connected to central terminal IB of choke coil Cthrough resistor I5.

In this form of apparatus a composite unidirectional voltage wave of onesign derived from the three-phase source of supply is impressed onone-terminal of choke coil C and a similar cornposite wave of theopposite sign and displaced in phase derived from the three-phase'sourceis impressed on the other terminal of the choke coil. Thus a triplefrequency output voltage is Resistor i5 constitutes a consuming load forthe direct current component. Thevwave form of the current supplied tothe load circuit may be improved by the provision of suitable saturablechoke coils connected in the primary winding circuits and operating asdescribed in my copending application referred to hereinbefore.

It is to be understood the invention is not, however; limited to theparticular forms here disclosed by way of example.

Although I have herein shown and described only two forms of apparatusembodying my invention, it is understood that various changes andmodifications may be made therein within the .scope of the appendedclaim without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

In combination, a two-phase source of alterhating current of a givenfrequency, a first and a second full wave rectifier, said rst rectifierhaving its input terminals connected to a first phase of said source,said second rectifier having its input terminals connected to a secondphase of said source, a choke coil having one outside terminal connectedto the positive output termina] of said first rectifier and its otheroutside terminal connected to the positive output terminal of saidsecond rectifier, means including a resistor to connect a mid terminalof said coil to the negative output terminals of said rectifiers, and aload circuit coupled to said choke coil to receive alternating currentof double said given frequency due to the voltages made to appear at theoutput terminals of said coil.

ALEC HERVEY BENNETT WALKER.

REFERENCES CITED FOREIGN PATENTS Country Date France July 17, 1934Number

